Thermite
by NPYD
Summary: [4x20 'The Limey'.] She can't stand this new Castle. He's smug and his jokes are cruel and deep down she's sure she deserves it, but that doesn't make it hurt less that he's pulling away.


She can't stand this new Castle. He's smug and his jokes are cruel and deep down she's sure she deserves it, but that doesn't make it hurt less that he's pulling away. It doesn't make the wondering why any easier. It certainly doesn't ease the ache that settled like motor oil into her lungs the moment that he showed up with... _her_. She pushes the thought out of her mind as much as she can, as much as she's been able to all night, until she spots him, lurking around the deserted precinct and looking significantly worse for wear. It all floods back.

He's leaned against Ryan and Espo's desk when she arrives at the precinct, intending to make for her locker for the change of clothes she keeps for emergencies. She just wants to get out of this stupid dress. It was wasted on a night like this. Wasted on her. It itches on her body; the memory of how she acquired some weeks ago after the incident with the tiger clings to every sinuous curve of it. She'd bought it on impulse with vague intentions of wearing it on her first formal night out with the author, the nameless event that she'd been so certain they'd someday soon attend together.

She'll just have to burn it when she gets home. She doesn't need a reminder hanging in her closet like a waiting noose to remind her of what she killed.

His lips curl into a smug smirk that he has no right to wear. "Have a nice time with Captain Kangaroo?" he asks. She wants to slap him.

"He's English!" she defends. Castle grunts with dark amusement as he saunters up to her, daring her to tell him to get out of her personal space, because he's most definitely in it. He's never had much of a concept of personal space, but before it's been (mostly) innocent. Annoying as reading over her shoulder could be, she'd grown to tolerate - even like - it, and crave the warmth he radiated.

"That's the worst accent I've ever heard."

There's no warmth now.

Was he always this tall? How come she's never noticed how imposing he can be? It's an odd time to arrive at such a conclusion. Never in four years has she found him personally imposing. He's Castle. Goofy, sweet, exceedingly-helpful and patient Castle. Vaguely, she knew he was capable – she's seen him throttle trained assassins with the look of cold rage that said he was perfectly capable of any extreme, given enough motivation, and she still wonders where that comes from – but even then, she's never felt it directed at her.

Except for right now. Of course she knows he'd never physically hurt her (though that might be better), but that same cold fury lurks behind his stony eyes. Right now, she knows exactly the limits of his patience, and realizes once again too late that she's pushed too far and he's finally broken. And it's her fault. She's broken him and it's all her fault.

Unless... unless she overestimated his feelings? Did he not mean what he said when she was dying? She knows how that goes. People say all kinds of things when someone is dying. She said all kinds of things when she thought her dad would drown himself down a bottle. Things she didn't mean. Not for the first time, she convinces herself that that was just it – it was just Castle saying what he thought she should hear, should that have been the last time he could speak to her. Comfort to a dying once-muse, to hear that she was loved one last time.

Kate deflects, feeling the overwhelming urge to bolt and attempt to outrun the sob threatening to choke her. "Go home, Castle; we got the guy's prints. Nothing more to be done here."

She needs him to go home. She feels worse than nude in this dress; she can still feel every eye in the room at the party on her. Every eye except his. He won't even look directly at her now. He's staring obstinately somewhere over her shoulder, far away and looking as if he wishes it were further. She needs him to follow fucking orders, for once in his life, because if he stays here a second longer...

He expels a puff of air from his nose, his lips still curled into half of a smirk. "I'll go when I'm good and ready."

"GO!" the syllable expels itself from her, hurls itself at him, "go back to Jacinda or Gina or Ellie or whoever it is tonight!" Her hands both fly to cover her mouth in shock. But it's too late (she's always too late); her outburst has escaped.

"Fine," her partner growls, his jaw tensing with the grind of his teeth and his face creeping red with simmering anger, "I will."

Her filter's already nine-tenths gone and the last of it leaves her when he's turning to walk out. As instructed.

"How long did you know her before you fucked her, Castle?" the precinct is dead, and her voice echoes through the bullpen, "twenty whole minutes?"

Just like that he's in her face again, glowering down at her like she's just tread on his last nerve and he's finally got an excuse to tear into her.

"You can kick me out and hurl your abuses at me and pretend that you don't know what's going on all you want, but don't you dare act self-righteous," he seethes, his nostrils flaring and the cut of his jaw adding to his intimidating appearance, "don't you dare tell me what to do or presume what I've done. You've made it abundantly clear that you don't want me, so what right do you have to any say in what I do with my life?"

What?

She must have verbalized it, but she's too numb to feel the exclamation leave her mouth.

"You heard me," he hisses at her, "I'm sure it comes as a surprise to you, _Princess_ , but you can't have it both ways. You can't ask me to wait and then not even do me the courtesy of telling me that you've changed your mind, or that you never felt anything to begin with. I'm not taking that."

It's as if he's slapped her. She latches onto the easiest part of his harangue and locks her jaw.

"Changed my mind? You think I've changed my mind? You're the one who's changed!" He has, he's changed and it was so sudden she's got whiplash from it, and she doesn't even know why his patience has suddenly run out, only that it has. She's overwhelmingly sad, but anger is, as always, easier. "You're the biggest flake I've ever met! I mean I get it; you had to say _something_ because you can't stand to keep your mouth shut, and you didn't expect I'd survive to remember it. But..."

Beckett abruptly runs out of steam.

"But what?" for the first time in weeks, she hears Castle again. Not the smug imitation her partner, friend, almost-lover has been replaced with as of late. "Bec- Kate?"

She chances a look at him and hears herself inhale sharply. There's a desolation to him she never thought possible. Like he's watching his last hope die. Like he doesn't know where to find the strength to go after it.

The events of the last few weeks begin to link up in her mind with what he's said tonight. _You don't want me. You've changed your mind_. It's not the first time in weeks, as much as the first time since the bombing. His entire attitude changed after that. She thought it was burnout at first. But he knows things. He knows things he...

He heard her say that she remembered every second of her shooting.

 _Oh god._

"Castle," her anger dissipates instantly, and there's not even room – yet – for self loathing. She just needs to fix it. Whatever there is left to be fixed. He steps backward and out of range when she reaches for his hand. She supposes she deserves that. But he doesn't leave entirely. That's something. Not much, but something. She has to pull him back. "We need to get out of here and talk. Now."

Whether it's force of habit to follow her out, or he has one last ounce of patience he's found for her, she doesn't know. All she knows is that she's never been more grateful for the footsteps in time behind hers that she's taken for granted for far too long.

The cruiser isn't exactly neutral territory, but Castle's Ferrari isn't, either. He pulls himself into the driver's seat, not bothering to open the door for her or tell her to get in. She takes his barely-indicated offer just the same, timidly settling in the passenger seat. Chancing a look up, she catches his waiting expression. He wants her to say something. For the life of her, she doesn't know what it should be, what could possibly help now.

"Can we go back to your place?" she asks, consciously looking for a way to rebalance the equation a little bit. Give him back some say when she's selfishly and thoughtlessly taken it all away. He doesn't answer immediately.

"Yours would be preferable," Castle admits tentatively, "I think it's better-" she hears _safer_ "-if Alexis isn't around this insanity right now." Isn't around her, he means. It's fair. He's already been more than fair to her.

"Okay."

She leans against the door and waits for Castle to make the next move.

Ten blocks later, he finally speaks.

"I couldn't sleep with her," he blurts out. "Jacinda. I tried."

"Castle, I didn't mean – it doesn't-"

"It's not for your benefit," his voice is deep and steely, still holds an edge of anger, but he's under control, at least. He hasn't gotten out of the car or dropped her in the street. There must still be something for him to hold on to.

"I can't keep up like this," he tells her, the jagged creak of his words driving a knife between her breasts right overtop her still-healing scar. "If there's nothing, if you feel nothing for me, tell me. Tell me and let me move on. I can keep my promises, keep the secrets I need to keep. But I can't do this any more. I can't be your friend."

He's making her choose.

"Why not?" she asks, "we function like this." No, they don't, and she's the furthest thing from functioning. But she can't lose him. She'd cease to function at all and she needs him any way she can keep him. Cruelly. Selfishly. She needs him.

" _You_ function. I don't," he corrects, slightly more under control, "a lot of me doesn't." There's a bitter and shamed edge to that and she wonders just what he means, until she remembers what he said about trying to sleep with the flight attendant.

Oh. _Oh_.

"Are you okay?" Of course he's not. She knows he's not. That's why they're here. Neither of them are okay.

"Physically, yes," Castle snorts indignantly, "Fairly certain you know that, from what happened when we were pushing that chest, the day with the tiger." She knew all too well. She thought he knew that it affected her just as much. She tried to tell him, to promise him that someday, _without_ the tiger, they'd get there. "It's... it's all mental."

She's hurt him so much. In such terrible ways. He's only tried to love her. He... maybe still loves her? But she's no good for him. She does nothing but hurt him.

"Why can't we just stay friends?" she asks again. If he's her friend, why can't he keep being that, if she's too broken for anything else, if she has no hope of giving them what they both need?

Assessing her sadly, Castle sighs, the lacerated defeat of heartbreak making him look older and exhausted.

"Because there's no room for anyone else as long as you're in my life, in any form. Because if I could ever..." – he won't say the words again; she thinks it'd kill him – "feel a fraction of the way I feel about you, for someone else, it wouldn't be fair to her. Or you. Or me. Because I know, the moment you called, I'd come running back. You'd always come first, whether I wanted you to or not, whether I hated you for it or not."

They're stalled in midtown traffic, separated by a leather divider and a world of decisions. Castle keeps his eyes firmly fixed on the road that inches by outside and leans back in his seat as stiffly as if he'd just been given a month to live.

"What if it doesn't work?" Kate grasps for another reason, she's sure there's a good one, to not throw herself at him now and tell him everything that's in her heart, but can't find one. The fear of failure is all that she has left to keep him at bay, and at last she sees that even that's invalid. Second chances are not endless in supply. Neither of them are going to recover this time if they fail. Neither of them are going to recover if they don't try, which is failure by default and little better.

There's a stopper in the bleeding between them, a halt to the life draining out, and incrementally, Castle raises his eyes to hers.

"What are you saying?"

Kate swallows, her throat so dry and tight that it feels like suffocation instead.

"I don't know." A fresh wave of guilt slaps her. They both know that's a lie.

"No," Castle refuses, his eyes darting from the road in front of him to her, "don't give me that shit." She's a little taken aback by his tone, the way he says it tells her he's so close to done, and she can't exactly fault him for it. Taking a deep breath, she tries again.

"What if we try a... _relationship,_ and it doesn't work?"

For punishing moments, the central word she's long-since avoided uttering hangs in the air, pulsing into her like snake venom, firing off her nerves at odd ends and wreaking havoc on her heart's rhythm. He's not saying anything. Why isn't he saying anything?

"I don't think I can deal with it if we fail," she admits quietly.

He doesn't respond immediately, just keeps his eyes ahead. He pulls to the curb outside her building and parks before he turns his full attention to considering her, searching and probing for a hint of insincerity or dishonesty.

"You'd survive," Castle declares, no sarcasm or superficial appeasement in it. "You already have. We both have. We've already failed – a few times, no less – and we've both survived."

Kate chokes on a humorless laugh, recognizing the truth of it. It's almost comforting. They may have never had the guts to say it, but it was true, that they'd already lost each other on the edge of something more a few times. "Same time every year, it seems."

"Doesn't have to be that way," her partner argues.

Pulling into her parking space where the cruiser usually rests and killing the engine, Castle makes his last offer.

"You can go," he begins, and she panics, thinking it's the end for real this time and he's dismissing her. Castle holds up a hand to stop her from bolting, as if he knew that was coming. "You can go now and I'll go home and that's it. There's no sense dragging it out if this is too big of a risk to take – and I understand that it might be."

"Or?" She needs there to be an _or._

"Or... if you need more time, I can give it. I'm not going to push you, I just..." she can see him fraying again, "I thought that you didn't care at all. Now that I know that's not the case, I can leave it here for tonight and we can pick it up again when you're ready. If that's what you want."

Is it?

Barely brave, Kate drinks in a gulp of air, vital oxygen that doesn't quite satiate her lungs in the way it should, the effort of taking it pulling at the dent in her chest just beneath the bust of her dress. His dress. It was always his, and if she can salvage anything tonight, maybe the space on her floor she'd envisioned it occupying won't go unrealized after all.

"And if I don't want to leave it here?"

Castle looks straight at her – no, straight through her – and his gaze burns beneath her dress, beneath her skin and bones into her molecules, as if he could pick her apart that way.

"I need to know what you want," he answers at long last, "and don't tell me anything you're not certain you'll still mean in the morning." The implication's thick in the starvation of his voice; he's laid out for her precisely what each course he's left her to decide on entails.

Anyone else, she'd say it was forward. Presumptuous. Forceful, even. And it's all of those things. It is also inevitable, and she's known it would happen this way for them nearly from the beginning. That there'd be no careful dating – a getting to know you period is laughable at this point – or slow buildup. She's imagined their beginning a thousand ways, but never was it particularly in question that they'd come to a point where they simply couldn't do anything else but fuse together and leave the fallout to chance.

"What do you need?"

She doesn't need more time. There's no use putting a stay on always or almost. This is it. Their line between the past and the future.

Kate draws it with a word.

"You."

* * *

 _Leaving this marked complete for now._

 _Much love for and apologies to Morgan and Dorrie, whose beta'ing I sought and then rudely disregarded because this story decided it wanted to be something else. Thank you both._

 _To all readers and reviewers as well, thank you. Your feedback and enthusiasm is the greatest._


End file.
